Dual cycle fan jet engine for stol aircraft with augmentor wings

ABSTRACT

A dual cycle fan jet engine suitable for use in STOL aircraft with augmentor wings is disclosed. In a cruise mode of operation, primary air and fan air from a fan jet engine are axially exhausted rearwardly in a conventional manner. In an augmentor mode of operation, the primary air is diverted by valves through an augmentor turbine where it is expanded and exhausted at a relatively low velocity, and the fan air is diverted by valves through an augmentor compressor driven by the augmentor turbine. The supercharged output of the augmentor compressor is directed via wing ducting to the augmentor flaps of the associated augmentor wing.

United States Patent [191 Kelley 1 DUAL CYCLE FAN JET ENGINE FOR STOLAIRCRAFT WITH AUGMENTOR WINGS [75] Inventor: George S. Kelley, Bellevue,Wash.

[73] Assignee: The Boeing Company, Seattle,

Wash.

[22] Filed: Feb. 14, 1974 [21] Appl. N0.: 442,330

[52] U.S. Cl 244/12 D; 60/225; 60/226 R; 60/229; 244/42 CC [51] Int. Cl.B64C 15/06 [58] Field of Search.... 244/12 D, 23 D, 23 B, 12 R, 244/12A, 12 B, 42 CC, 42 CD, 6, 7, 23 R;

1 July 8,1975

3,761,042 9/1973 Denning 244/12 D FOREIGN PATENTS OR APPLICATIONS1,273,332 8/1961 France 244/12 D Primary Examiner-Trygve M. BlixAssistant ExaminerGalen L. Barefoot Attorney, Agent, or FirmChristensen,O'Connor, Garrison, & Havelka [57] ABSTRACT A dual cycle fan jet enginesuitable for use in STOL aircraft with augmentor wings is disclosed. Ina cruise mode of operation, primary air and fan air from a fan jetengine are axially exhausted rearwardly in a conventional manner. In anaugmentor mode of operation, the primary air is diverted by valvesthrough an augmentor turbine where it is expanded and exhausted at arelatively low velocity, and the fan air is diverted by valves throughan augmentor compressor driven by the augmentor turbine. Thesupercharged output of the augmentor compressor is directed via wingducting to the augmentor flaps of the associated augmentor wing.

11 Claims, 8 Drawing Figures DUAL CYCLE FAN JET ENGINE FOR STOL AIRCRAFTWITH AUGMENTOR WINGS BACKGROUND OF THE INVENTION This invention isdirected toward jet engines, and more particularly, toward jet enginessuitable for use with STOL aircraft.

One of the problems with modern air travel, and in particular jettravel, is the cost of developing and maintaining airports. In general,modern airports are expensive because jet aircraft require relativelylong runways for takeoff and landing. Because they are expensive, modernairports can only be justified when they are located near largemetropolitan areas where there is a large demand for air travel. Inthese areas, the cost is even greater because the land values adjacentlarge metropolitan areas are considerably higher than they are in other,less densely populated, areas.

In any event, in recent years, attention has been directed towarddeveloping aircraft which can land and take off from shorter runways.These aircraft are commonly known as short take-off and landing (STOL)aircraft. Because STOL aircraft use much shorter runways, the size ofthe airports associated with this type of aircraft is greatly reducedmaking small metropoli tan area airports more feasible.

One type of STOL aircraft that has been proposed utilizes fan jetengines and includes a diverter for diverting fan air from the jetengine into wing ducting. The diverted air exits from the wing ductingand exhausts through augmentor flaps which are retracted to form aportion of the wings during cruise. The flaps are movable and adjustablein a manner such that the fan air assists in lifting the aircraft at aconsiderably lower velocity than the aircraft can be lifted without theuse of ducted fan air and augmentor flaps whereby the aircraft can landon and take off from shorter runways. By properly designing theaugmentor wing, the noise output of the aircraft can be kept to a lowlevel.

While STOL aircraft of the foregoing nature have been somewhatsatisfactory in that they have a low noise output and improved liftcapability, certain problems exist. For example, the pressure of fan airfrom a standard fan jet engine is inadequate for use with augmentorflaps. Thus, standard fan jet engines must be modified in order toincrease the pressure of their fan air. Such modifications, however,decrease the efficiency of the engines under cruise conditions, whenaugmentor air is not needed.

Therefore, it is the object of this invention to provide a new andimproved STOL aircraft engine.

It is a further object of this invention to provide a low noise fan jetengine suitable for use with a STOL aircraft that has good efficiencyunder cruise conditions.

SUMMARY OF THE INVENTION In accordance with principles of thisinvention, a dual cycle fan jet engine suitable for use in a STOLaircraft having augmentor wings is provided. In a cruise mode ofoperation, the primary and fan air outputs of a fan jet engine areaxially exhausted to the rear in a conventional manner. In an augmentormode of operation, the primary air output of the fan jet engine isdiverted downwardly through an augmentor turbine. The augmentor turbineremoves energy from this air and exhausts it at a relatively lowvelocity. Hence, this air has a low noise content. At the same time, thefan air is diverted upwardly through an augmentor compressor driven bythe augmentor turbine. The compressed or supercharged output of theaugmentor compressor is ducted through the wing in a manner such that itis exhausted through the augmentor flaps of the associated wing.

In accordance with further principles of this invention, the primary andfan air flow, either axially in the cruise mode of operation or to theaugmentor turbine/- compressor in the augmentor mode of operation, iscontrolled by opening and closing valves.

In accordance with still other principles of this invention, one valveis opened and closed to control the axial flow of primary air, and asecond valve is opened and closed to control the axial flow of fan air.A third valve controls the flow of primary air through the turbineblades of the augmentor turbine. and a fourth valve controls the flow offan air through the compressor blades of the augmentor compressor.

It will be appreciated that the foregoing brief summary that theinvention provides dual cycle fan jet engines suitable for use in a STOLaircraft for diverting and compressing fan air. The compressed fan airis exhausted through the augmentor flaps of the augmentor wings of theaircraft. The fan air is compressed by a compressor driven by a turbinewhich in turn is driven by the primary air exhausted by the fan jetengine. Be cause the air emitted from the turbine has a relatively lowvelocity, it has a relatively low noise content. The augmentor air alsohas a relatively low noise content because the augmentor wing can bedesigned such that augmentor air is emitted in a low noise contentmanner.

It will also be appreciated that. in addition to the low noise augmentormode of operation, the dual cycle fan jet engine of the invention alsohas a cruise mode of operation suitable for high altitude flying wherenoise is no problem. The efficiency of the engine in the cruise mode ofthe operation is much better than in the augmentor mode of operation.Thus, the invention is flexible in that it allows the STOL aircraft totake off from or land on a short runway, yet cruise at relatively highaltitudes in an efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing objects and many of theattendant advantages of this invention will become more readilyappreciated as the same becomes better understood by reference to thefollowing detailed description when taken in conjunction with theaccompanying drawings wherein:

FIG. 1 is a perspective view of a STOL aircraft;

FIG. 2 is a cross-sectional side view partially in section illustratinga dual cycle fan jet engine formed in accordance with the invention.

FIG. 3 is a perspective view of a vane valve suitable for use by theinvention;

FIG. 4 is a front view of a vane valve of the type illus trated in FIG.3 in an open state;

FIG. 5 is a front view ofa vane valve of the type illustrated in FIG. 3in a closed state;

FIG. 6 is a side view of a vane suitable for use in a vane valve of thetype illustrated in FIGS. 3 through 5;

FIG. 7 is a front view of an annular rotary valve suitable for use bythe invention, and,

FIG. 8 is a perspective view of an annular rotary valve of the typeillustrated in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT The STOL aircraft 11 illustratedin FIG. I comprises a fuselage 13; a vertical stabilizer I5; ahorizontal stabilizer l7; wings l9; and, engines 21. The engines 21 aresupported beneath the wings I) by struts 23. While only two engines 2]are illustrated in FIG. 1, additional engines may be utilized asnecessary. The wings 19 are augmentor wings and include augmentor flaps25. The augmentor flaps 25 are movable so that air generated by theengines and ducted through the wings can be exhausted through the flapsin a manner that increases the lift capability of the wings, as is wellknown in the art.

FIG. 2 illustrates a dual cycle fan jet engine 21, formed in accordancewith the invention. hung from one of the Wings 19 by one of the struts23.

The dual cycle fan jet engine 21 illustrated in FIG. 2 comprises a fanjet engine 33. In a conventional manner, outside air is received at theinlet 42 of the fan jet engine 33 and compressed to create primary air.The primary air 35 axially exits from the rear 37 of the front engine33. During cruise, this air is exhausted rearwardly 36 via a horizontalduct 34 as hereinafter described. Other outside air also received at theinlet 42 of the primary engine 33 is compressed into fan air 44. The fanair 44 axially flows through an enclosed space 39 surrounding thehorizontal duct 34 and exhausts from the rear of the engine nacelle 4],during cruise. Thus, in the cruise mode of operation, the primary andfan air axially flow in a conventional manner, ie. the outside air iscompressed into primary and fan air and the compressed air is exhaustedaxially rearwardly in a conventional manner.

In addition to the cruise mode of operation, the dual cycle fan jetengine illustrated in FIG. 2 includes an augmented mode of operation. Inthe augmented mode of operation, the primary air 35 is diverted from itsaxial flow path. The diverted primary air 35 is applied to the blades 46of a plural stage augmentor turbine 49 mounted in a lower vertical duct50 located beneath and having access to the horizontal duct 34.Diversion ofthe primary air 35 in this manner is controlled by twovalves, a primary air exhaust valve 47 and an augmentor turbine inletvalve 45. While the primary air exhaust valve 47 is illustrated as avane valve and the augmentor turbine inlet valve is illustrated as anannular rotary valve, either of these valves can be formed in othermanners, well known to those skilled in the art. Moreover, they can bereversed or both formed in a similar manner. That is, they both could bevane valves or they both could be annular rotary valves.

The primary air exhaust valve 47 is mounted in the horizontal duct 34downstream from the rear 37 of the fan jet engine. The lower verticalduct is located between the rear 37 of the fan jet engine 33 and theprimary air exhaust valve 47. The augmentor turbine inlet valve 45 ismounted in the lower vertical duct 50 between the horizontal duct 34 andthe turbine blades 46. When the primary air exhaust valve 47 is closedand the augmentor turbine inlet valve 45 is opened, energy in theprimary air 35 acting on the blades 46 rotates a ver tical shaft 53 in aconventional manner. Because en ergy is removed from the primary air 35,the air 48 ex hausting from the augmentor turbine 49 through a pluralityof louvers 51 has a low velocity. Because it has a low velocity. it hasa low noise content. Preferably, this air is exhausted downwardly andrearwardly so as to provide lift. However, it may be exhausted in otherdirections. if desired.

Also, forming part of the apparatus of the invention and used during theaugmentor mode of operation is an augmentor compressor 57; a fan aircontrol valve 55; and. an augmentor compressor outlet valve 58. Theaugmentor compressor 57 includes a plurality of blades 52 rotated by thevertical shaft 53 in a conventional manner. The blades 52 are mounted inan upper vertical duct having access from below to the fan air 44exhausted by the fan jet engine 33. Mounted above the blades 52 of theaugmentor compressor 57, as viewed in FIG. 2, is the augmentorcompressor outlet valve 58.

The augmentor compressor outlet valve 58 may also take on a variety offorms. For purposes of illustration, it is illustrated as comprising aplate 59 rotatable about a hinge point 62 by a hydraulic cylinder 6].When the augmentor compressor outlet valve is open, fan air compressedby the augmentor compressor 57 is allowed to flow into a duct '73located in the strut 23. When the augmentor compressor outlet valve isclosed, this flow is prevented.

Cooperating with the augmentor compressor outlet valve 58 is the fan aircontrol valve 55. The fan air control valve 55 annularly surrounds thehorizontal duct 34 and either allows fan air to flow past the outside ofthat duct or prevents such air flow. The fan air control valve allowssuch fan air flow when the dual cycle fan jet engine of the invention isin its cruise mode of operation and inhibits such flow when it is in itsaugmentor mode of operation.

In the foregoing manner, fan air is compressed and supplied to the strutand wing duct 73. The strut and wing duct 73 directs the compressed fanair through the strut 23 and wing I9 and emits it into a region betweena lower flap 77 and an upper flap 8]. The strut and wing duct and itsexhaust region are formed such that the exiting fan air has a low noisecontent. as is well know in the art.

As will be understood by those skilled in the art and familiar withaugmentor wings, the fan air applied between the lower and upper flaps77 and 81 tremendously increases the lift capability of the wing 19 and,thus, allows the STOL aircraft 11 to take off from and land onrelatively short runways. This is the augmented mode of operation.

While the augmented mode of operation greatly improves the liftcapability of the aircraft, it is relatively inefficient at cruise speedeven if the flaps are moved so as to streamline the wing 13 asillustrated by the dashed lines in FIG. 2. In order to overcome thisprob lem, as the STOL aircraft achieves altitude, the dual cycle fan jetengine of the invention shifts from its augmented to its cruise mode ofoperation. This shift is created by the augmentor tubine inlet valve 45closing, the primary air exhaust valve 47 opening, the fan air controlvalve 55 opening and the augmentor compressor outlet valve 58 closing.The primary and secondary engines then operate in a conventional manner.

.ts previously indicated, the augmentor compressor outlet valve 58 maytake the form of a plate 59 operated in a rotational manner about ahinge 62 by a hy draulic cylinder 61. The other valves may take on a variety of forms. One such form is generally illustrated in FIGS. 3through 6 and another is illustrated in FIGS. 7 and 8.

The valve illustrated in FIGS. 3 through 6 is an annular vane valve andcomprises a coaxial hub 82 surrounded by a circular rim 83. Extendingradially outwardly from the hub to the rim are a plurality of vanes 84.The vanes are aerodynamically shaped in crosssection and rotatable abouttheir longitudinal axes 85 between two extreme positions. In one extremeposition (FIG. 4), the vanes allow air to flow between the hub 82 andthe circular rim 83 and create a minimum amount of restriction to suchflow. When in this position, the longitudinal axes 86 defined by theiraerodynamic shapes are aligned with the direction of the air flow. Inthe other extreme position (FIG. 5), the vanes 84 prevent the flow ofair between the hub 82 and the circular rim 83. Positions in between theextreme positions provide a controlled amount of restriction to such airflow.

The vanes 84 are movable between their extreme positions by anysuitable, well known, means. For example, the vanes may be gear coupledtogether by gears locked inside of the circular rim 83 in a manner suchthat movement of one gear will cause a simultaneous movement of all ofthe gears and, thus, their associated vanes. Moreover, the vanes cantake on a variety of shapes. They can diverge outwardly, as illustratedin FIGS. 3 through 6. Or, they can be of constant width. Moreover, whenthe valve is closed, the vanes can overlap by either a small amount or alarge amount. Further the amount of overlap can be the same or vary fromthe hub to the rim.

While a vane valve suitable for use as the primary air exhaust valve 47has been illustrated in FIGS. 3 through 6, it will be appreciated thatthe same type of valve can be used for the fan air control valve. Inthis case, the hub will include a central aperture large enough tosurround the outside of the horizontal duct 34.

The valve illustrated in FIGS. 7 and 8 is a rotary annular valve andcomprises a pair of circular vaned plates 89 and 91. Each of the vanedplates includes a plurality of radial vanes 87 separated by open regions88. The vanes 87 and the open regions are of approximately the same sizein area and shape.

The vaned plates are rotatable with respect to one another about acentral axis 93 by any suitable means. One such means requires one ofthe plates to be fixed and the other to include a plurality ofperipheral gear teeth 94. The gear teeth 94 coact with a gear 97 rotatedby a suitable pneumatic or electrical motor 98 (FIG. 2). When the gear97 is rotated for a short distance in one direction, the vanes 87 becomepositioned such that apertures are formed through the two plates. Whenthe gear 97 is rotated in the opposite direction, the vanes becomepositioned such that no apertures exist through the plates.Alternatively, the vanes may be placed in a multitude of positionsbetween these two extreme positions so as to control the size of theapertures formed through the plates. In a similar manner, a cylindricalannular rotary type valve may be utilized to form the fan air controlvalve 55 which surrounds the secondary engine 35. Also, as illustratedin FIG. 4, the shaft 53 passes through and lies coaxial with the centerof a valve of this type when it is used to form the augmentor turbineinlet valve 45.

It will be appreciated from the foregoing description of the preferredembodiment that a dual cycle fan jet engine suitable for use in a STOLaircraft is provided by the invention. The engine can operate in astandard cruise mode or it can operate in an augmented mode. In the caseof the cruise mode of operation. fan air is not applied to the augmentorflaps of the aircraft which are then in a streamlined position. In theaugmentor mode of operation, compressed fan air is applied to theaugmentor flaps. Also in the augmentor mode. the primary air from thefan jet engine is deflected downwardly to revolve the shaft of aturbine. The thusly driven turbine shaft drives a compressor whichcompresses fan air. It is this compressed fan air that is ducted to theaugmentor flaps of the augmented wing of the aircraft so as to improvethe lift capability of the wing.

Because the air exhausting from the turbine has a low velocity, it is alow noise content. The compressed air exiting from the compressor bladesand ducted to the augmentor flaps also has a low noise content if theaugmentor ducts and associated components are formed in a suitablemanner. Thus. the engine of the invention generates a limited amount ofnoise in the augmentor mode of operation. On the other hand, it ishighly efficient in its cruise mode of operation when its noisegeneration is of little consequence.

While a preferred embodiment of the invention has been illustrated anddescribed, it will be appreciated by those skilled in the art and othersthat various changes can be made therein without departing from thespirit and scope of the invention. Hence, the invention can be practicedotherwise than as specifically described herein.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

I claim:

I. A dual cycle fan jet engine suitable for use in a STOL aircrafthaving ducted augmentor wings, said dual cycle fan jet enginecomprising:

a fan jet engine adapted to generate primary air and fan air;

air driven means for extracting energy from airflow and generatingmechanical power in accordance therewith;

air compression means for compressing air, said air compression meansconnected to said air driven means so as to be powered by the mechanicalpower generated by said air driven means;

a horizontal duct extending rearwardly from the primary air outlet ofsaid fan jet engine;

a nacelle surrounding said fan jet engine and said horizontal duct fordirecting the fan air from said fan jet engine about said horizontalduct;

a first vertical duct connecting said horizontal duct to the inlet ofsaid air driven means;

a second vertical duct connecting said nacelle to the inlet of said aircompression means;

a first valve located in said horizontal duct, said first vertical ductbeing located between the rear of said fan jet engine and said firstvalve;

a second valve surrounding said horizontal duct, said second verticalduct being located between said fan jet engine and said second valve;

a third valve located in said first vertical duct between saidhorizontal duct and the inlet of said air driven means; and,

a fourth valve, located on the side of said air compression means remotefrom the side where said air compression means receives said fan air,for con trolling the flow of fan air from said nacelle to said aircompression means.

2. A dual cycle fan jet engine as claimed in claim 1, wherein said firstvertical duct is located beneath said horizontal duct and wherein saidsecond vertical duct is located above said horizontal duct.

3. A dual cycle fan jet engine as claimed in claim 2, wherein said airdriven means comprises an air turbine and wherein said air compressionmeans comprises an air compressor.

4. A dual cycle fan jet engine as claimed in claim I, wherein said airdriven means comprises an air turbine and wherein said air compressionmeans comprises an air compressor.

5. in a STOL aircraft including ducted augmentor wings adapted to directair energized by a jet engine to augmentor flaps, said augmentor flapsadapted to direct said air generally downwardly and, thereby, aug mentthe lift provided by the aerodynamic shape of the wings of said STOLaircraft, the improvement comprising a dual cycle fan jet enginecomprising:

a fan jet engine adapted to generate primary air and fan air;

air driven means for extracting energy from air flow and generatingpower in accordance therewith. said air driven means having an inlet incommunication with the primary air of said fan jet engine;

air compression means for compressing air, said air compression meansconnected to said air driven means so as to be powered by the powergenerated by said air driven means and said air compression means havingan outlet in communication with the duct of one of said ducted augmentorwings of said STOL aircraft;

duct means, mounted between the rear of said fan jet engine said airdriven means and said air compression means. for ducting primary airfrom said fan jet engine between an axial exhaust and said air drivenmeans. and for ducting fan air from said fan jet engine between an axialexhaust and said air compression means; and,

control means for selectively controlling the flow of primary airbetween said axial exhaust and said air driven means. and forselectively controlling the flow of fan air between said axial exhaustand said air compression means.

6. The improvement claimed in claim 5 wherein said air driven meanscomprises an air turbine and wherein said air compression meanscomprises an air compressor. the shaft of said air turbine beingconnected to the shaft of said air compressor so that said aircompressor is mechanically powered by said air turbine.

7. The improvement claimed in claim 5 wherein said duct means comprises:

a horizontal duct extending rearwardly from the primary air outlet ofsaid fan jet engine;

a nacelle surrounding said fan jet engine and said horizontal duct fordirecting the fan air from said fan jet engine about said horizontalduct;

a first vertical duct connecting said horizontal duct to the inlet ofsaid air driven means; and,

a second vertical duct connecting said nacelle to the air inlet of saidair compression means.

8. The improvement claimed in claim 7 wherein said control meanscomprises:

a first valve located in said horizontal duct, said first vertical ductbeing located between the rear of said fan jet engine and said firstvalve;

a second valve surrounding said horizontal duct, said second verticalduct being located between said fan jet engine and said second valve;

a third valve mounted so as to control the flow of primary air from saidhorizontal duct to said air driven means; and,

a fourth valve mounted so as to control the flow of air from saidhorizontal duct to said air compression means.

9. The improvement claimed in claim 8 wherein said third valve islocated in said first vertical duct between said horizontal duct and theinlet of said air driven means; and, wherein said fourth valve islocated on the outlet side of said air compression means.

10. The improvement claimed in claim 9 wherein said first vertical ductis located beneath said horizontal duct and wherein said second verticalduct is located above said horizontal duct.

ll. The improvement claimed in claim 10 wherein said air driven meanscomprises an air turbine wherein said air compression means comprises anair compressor, the shaft of said air turbine being connected to theshaft of said air compressor so that said air compressor is mechanicallypowered by said air turbine.

1. A dual cycle fan jet engine suitable for use in a STOL aircrafthaving ducted augmentor wings, said dual cycle fan jet enginecomprising: a fan jet engine adapted to generate primary air and fanair; air driven means for extracting energy from airflow and generatingmechanical power in accordance therewith; air compression means forcompressing air, said air compression means connected to said air drivenmeans so as to be powered by the mechanical power generated by said airdriven means; a horizontal duct extending rearwardly from the primaryair outlet of said fan jet engine; a nacelle surrounding said fan jetengine and said horizontal duct for directing the fan air from said fanjet engine about said horizontal duct; a first vertical duct connectingsaid horizontal duct to the inlet of said air driven means; a secondvertical duct connecting said nacelle to the inlet of said aircompression means; a first valve located in said horizontal duct, saidfirst vertical duct being located between the rear of said fan jetengine and said first valve; a second valve surrounding said horizontalduct, said second vertical duct being located between said fan jetengine and said second valve; a third valve located in said firstvertical duct between said horizontal duct and the inlet of said airdriven means; and, a fourth valve, located on the side of said aircompression means remote from the side where said air compression meansreceives said fan air, for controlling the flow of fan air from saidnacelle to said air compression means.
 2. A dual cycle fan jet engine asclaimed in claim 1, wherein said first vertical duct is located beneathsaid horizontal duct and wherein said second vertical duct is locatedabove said horizontal duct.
 3. A dual cycle fan jet engine as claimed inclaim 2, wherein said air driven means comprises an air turbine andwherein said air compression means comprises an air compressor.
 4. Adual cycle fan jet engine as claimed in claim 1, wherein said air drivenmeans comprises an air turbine and wherein said air compression meanscomprises an air compressor.
 5. In a STOL aircraft including ductedaugmentor wings adapted to direct air energized by a jet engine toaugmentor flaps, said augmentor flaps adapted to direct said airgenerally downwardly and, thereby, augment the lift provided by theaerodynamic shape of the wings of said STOL aircraft, the improvementcomprising a dual cycle fan jet engine comprising: a fan jet engineadapted to generate primary air and fan air; air driven means forextracting energy from air flow and generating power in accordancetherewith, said air driven means having an inlet in communication withthe primary air of said fan jet engine; air compression means forcompressing air, said air compression means connected to said air drivenmeans so as to be powered by the power generated by said air drivenmeans and said air compression means having an outlet in communicationwith the duct of one of said ducted augmentor wings of said STOLaircraft; duct means, mounted between the rear of said fan jet engine,said air driven means and said air compression means, for ductingprimary air from said fan jet engine between an axial exhaust and saidair driven means, and for ducting fan air from said fan jet enginebetween an axial exhaust and said air compression means; and, controlmeans for selectively controlling the flow of primary air between saidaxial exhaust and said air driven means, and for selectively controllingthe flow of fan air between said axial exhaust and said air compressionmeans.
 6. The improvement claimed in claim 5 wherein said air drivenmeans comprises an air turbine and wherein said air compressioN meanscomprises an air compressor, the shaft of said air turbine beingconnected to the shaft of said air compressor so that said aircompressor is mechanically powered by said air turbine.
 7. Theimprovement claimed in claim 5 wherein said duct means comprises: ahorizontal duct extending rearwardly from the primary air outlet of saidfan jet engine; a nacelle surrounding said fan jet engine and saidhorizontal duct for directing the fan air from said fan jet engine aboutsaid horizontal duct; a first vertical duct connecting said horizontalduct to the inlet of said air driven means; and, a second vertical ductconnecting said nacelle to the air inlet of said air compression means.8. The improvement claimed in claim 7 wherein said control meanscomprises: a first valve located in said horizontal duct, said firstvertical duct being located between the rear of said fan jet engine andsaid first valve; a second valve surrounding said horizontal duct, saidsecond vertical duct being located between said fan jet engine and saidsecond valve; a third valve mounted so as to control the flow of primaryair from said horizontal duct to said air driven means; and, a fourthvalve mounted so as to control the flow of air from said horizontal ductto said air compression means.
 9. The improvement claimed in claim 8wherein said third valve is located in said first vertical duct betweensaid horizontal duct and the inlet of said air driven means; and,wherein said fourth valve is located on the outlet side of said aircompression means.
 10. The improvement claimed in claim 9 wherein saidfirst vertical duct is located beneath said horizontal duct and whereinsaid second vertical duct is located above said horizontal duct.
 11. Theimprovement claimed in claim 10 wherein said air driven means comprisesan air turbine wherein said air compression means comprises an aircompressor, the shaft of said air turbine being connected to the shaftof said air compressor so that said air compressor is mechanicallypowered by said air turbine.